Along with the recent development of image processing technology, image input apparatuses such as a digital camera for sensing an object and outputting its image signal are showing a remarkable consummation rush.
Image input apparatuses are roughly classified into a type that processes RGB signals as colorimetric data of an object and a type that executes multiple spectral distribution data processing by estimating the colorimetric data of an object illuminated with ambient light using the spectral distribution data of an object and that of the ambient light with which the object is illuminated. The former requires a short processing time and is advantageous in terms of cost because the processing is simple. On the other hand, the latter requires complex processing and therefore is disadvantageous in processing time and cost, though it can realize more accurate color reproduction.
Some apparatuses execute simple RGB/spectral distribution data processing while realizing accurate color reproduction by multiple spectral distribution data pressing by estimating spectral distribution data on the basis of received RGB signals.
In each of the above image input apparatuses, the internal signal processing system is limited to one of the RGB signal processing system, multiple spectral distribution data processing system, and RGB/spectral distribution data processing system, and has input and output units corresponding to one of the processing systems. That is, an image input apparatus having an RGB signal processing system has an RGB input unit and RGB output unit. An image input apparatus having a multiple spectral distribution data processing has a spectral distribution input unit and spectral distribution processing unit. An image input apparatus having an RGB/spectral distribution data processing system has an RGB input unit and RGB/spectral distribution processing unit.
Hence, input and output units for different signal processing systems cannot be connected to a single image input apparatus. For example, an output unit for a spectral distribution data processing system cannot be connected to an input unit for an RGB signal processing system.